Complex flow-path heat exchanger having U-shaped tube and cantilever combined coil

ABSTRACT

A complex flow-path heat exchanger having U-shaped tube and cantilever combined coil, which can achieve, in this type heat exchanger, a simple construction, a complex flow of steam within the same one heat exchange shell body, a high heat exchange efficiency, and a low energy loss. The technical gift of the present invention is that, after entering into the heat exchanger, steam firstly effects heat exchange on the U-shaped tube flow path shell side to be cooled and condensed, thereafter entering into flow path tube side of the cantilever combined coil, which are disposed within the same one shell, for a secondary heat exchange, and subsequently flowing out of the heat exchanger after being subcooled. Such steam-water heat exchanger having a complex flow path are advantageous in a small steam flow resistance of the U-shaped tube flow path shell side; a higher condensate water flow velocity in the cantilever combined coils flow path tube; a high heat exchange coefficient; good coordination of the temperature difference fields of the hot and cold fluids in the heat exchanger; and a high heat exchange efficiency. Therefore, the present heat exchanger can be a new generation product relative to the currently-used conventional low-temperature, low-pressure and corrosion-free heat exchangers.

FIELD OF THE INVENTION

The present invention relates to a steam-water heat exchanging device suitable to be used in multipurpose hot water supply systems.

BACKGROUND OF THE INVENTION

Conventional steam-water heat exchanging devices are largely divided into two types: one is a regenerative heat exchanger, such as a tube bank type heat exchanger and a submersible type heat exchanger, which is in form of usually a large-sized water storage container, in which tube bundles are arrange, steam flowing on the tube side, and water flowing in the shell side, wherein the heat exchanger has a large volume, the heat exchange efficiency thereof is low, and the energy loss thereof is high; the other is an instantaneous heat exchanger, commonly for example, an U-shaped tube type heat exchanger and a plate heat exchanger, etc., in which steam flows on the shell side, and water flows on the tube side, wherein the heat loss of this type heat exchanger is relatively high, because the temperature of the surface of the shell body is high. In a word, both of said heat exchangers employ a single flow path of the heat exchange medium, therefore, it is difficult to subcool the steam after it is condensed, consequently it is extremely difficult to prevent the steam from occurring to secondarily flash off; moreover, due to the quite low flow velocity in the condensate water tube of the steam-water heat exchanger employing the single flow path, the heat exchange coefficient is considerably low, furthermore, due to the fact that no phase change occurs, temperature-difference-field of hot and cold fluids are non-uniform, and the temperature difference fields of the hot and cold fluids can not coordinate with each other very well, so the heat exchange efficiency is low.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a complex flow-path heat exchanger having U-shaped tubes and cantilever combined coils, in order to achieve, in the type heat exchanger, a simple construction, a complex flow path of steam within the same one heat exchanger shell body, a high heat exchange efficiency, and a low energy loss.

The present heat exchanger is comprised of a water inlet pipe, a water outlet pipe, a steam inlet pipe, a condensate water outlet pipe, a shell body, U-shaped heat exchange tube bundles, a heat exchange element of cantilever combined coils, and etc. the lower half portion of the cylinder body of the heat exchanger is provided lower portion, wherein the upper half portion of the cylinder body is provided with the U-shaped heat transfer tubes serving as heat transfer elements, and the lower half portion of the cylinder body is provided with the cantilever combined coils serving as heat transfer elements. The operation process is described as follow: steam enters into the heat exchanger shell body through the steam inlet pipe, flowing through the U-shaped heat exchange tube bundles to be cooled and condensed, thereafter, entering the cantilever combined coils arranged in a plurality of groups for a secondary cooling, then the subcooled condensate water flowing out of the heat exchanger through the outlet pipe; on the other hand, the water to be heated firstly enters into a second segmental shell body in which the cantilever combined coils is provided, so as to be preliminarily heated, then flows into tubes of the U-shaped heat exchange tube bundles to be heated to the desired temperature, and the heated water flows out of the heat exchanger through the heated water outlet pipe.

The technical gist according to the present invention is as follows: after entering into the heat exchanger, steam is firstly cooled and condensed in the shell side of the U-shaped tube, thereafter entering into tube side of the cantilever combine coils, which are disposed within the same one shell, for a secondary heat exchange, and subsequently flowing out of the heat exchanger after being subcooled. Such steam-water heat exchanger having a complex flow path are advantageous in a small steam flow resistance of shell side of the U-shaped tube; a higher condensate water flow velocity in the cantilever combined coils; a high heat exchange coefficient; good coordination of the temperature fields of the hot and cold fluids in the heat exchanger; and a high heat exchange efficiency.

The cantilever combined coil has a fixed end, an absolutely free end, and a relatively free end. The element exhibits more spring characteristics with respect to vibration, enabling the continuously pulsating water flow to excite vibration more easily; moreover, the complex structure thereof performs an inhibiting effect during the vibration so that any change of any small force can prevent the continuation of the existing frequency vibration, while the main flow disturbance rapidly makes vibration to go on. Thus, the low frequency vibration within a given rang is thereby generated, making disturbance to the water flow, but no damage will be incurred due to strong vibration, and therefore a higher heat transfer coefficient can be achieved at low flow velocity. The characteristics of the structure of the cantilever combined coil in response to fluid induction vibration have the resonance characteristic when the flow pulsating frequency is equal to the structural natural frequency and the sub-resonance characteristics when the flow pulsate at ½ natural frequency. Consequently, the cantilever combined coil can be induced to vibrate by a lower frequency pulsating, and this vibration is in the sub-resonance region, so that no damage will be incurred due to violent vibration.

The present heat exchanger comprises the vertical type and the horizontal type. The arrangement of the cantilever combined coils according to the present invention in the present heat exchanger differs from that of the conventional tubular type heat exchange elements, thereby completely eliminating the need of the tube-plate coupling structural fashion, and instead directly connecting the cantilever combined coils in a plurality of groups onto the hot media tube in parallel. The structural form of the cantilever combined coils sets the heat exchange elements free out of the conventional tube-plate structure, so that the spatial arrangement of the heat exchanger is made more flexible, and the steam-water and water-water complex heat exchange within the same one shell can be realized; under the inducement of the pulsating flow, the energy distribution over the cantilever combined coils at respective natural frequency has a significant influence on the operating condition of the cantilever combined coil bundles. Upon experiments, the bending radius, and the diameter and the wall thickness of the circular tube of the cantilever combined coils can be screened out to determine the specific dimension of the different models, so that such constructed inducing vibration system as above makes the variation of the water velocity not to have a significant influence on the vibration, consequently, the cantilever combined coils can be adapted to the variation of different loads, while maintaining good vibration characteristics. The thermal efficiency of the present heat exchanger is more than 98%, and the maximum heat exchange capacity is 7 MW, and on the other hand, the heat source is generally saturated steam at the pressure 0.6 Mpa. The present heat exchanger can maintain the production output quite well, even when the steam pressure reduces to 0.1 MPa. The advantages of the present heat exchanger include the small size, the simple construction, a high energy utilization rate, etc., therefore, the present heat exchanger can be a new generation product relative to the currently-used conventional low-temperature, low-pressure and corrosion-free heat exchangers.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment and other aspects of the present invention will be best understood with reference to a detailed description of specific embodiments of the invention, which follows, when read in conjunction with the accompanying drawings, in which:

FIG. 1 schematically illustrates a cross section of the construction according to the present invention viewed from the front; and

FIG. 2 schematically illustrates the structure of the combined cantilever coils according to the present invention.

As shown in FIG. 1, the present heat exchanger is substantially comprised of an upper shell cover 1, a flange 2, a tube plate 3, a cylinder body 4, a lower shell cover 5, a supporting stand 6, a heated water outlet pipe 7, a spurting proof plate 8, a steam inlet pipe9, a baffle plate 10, U-shaped tubes 11, a partition plate 12, a condensate water outlet pipe 13, cantilever combined coils 14, a heater water inlet tube 15, and a drainage port 16.

As shown in FIG. 2, the structure of the cantilever combined coil has fixed ends A, B, an absolutely free and C, and a relatively free end D, the coil substantially comprising a balance weight 17, a circular casing cap 18, a clamp nut 19, a connecting sleeve 20, and circular heat transfer tubes 21, etc.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention will be described as follows. FIG. 1 and FIG. 2 show the construction on the whole. In the heat exchanger according to the present invention arrange vertically, the outlet pipe 7 of the heated water and the inlet pipe 15 of the heated water are disposed on the upper shell cover 1 and the lower shell cover 5 respectively, the steam inlet pipe 9 is disposed on the upper half portion of the cylinder body, and the drainage port 16 and the condensate water outlet pipe 13 are disposed on the lower shell cover.

The shell body of the heat exchanger is comprised of the cylinder body 4, the flange 2, and the oval shell cover and like. The lower half portion of the cylinder body 4 is provided with the partition plate 12 for dividing the cylinder body 4 into an upper portion and a lower portion, wherein the upper half portion of the cylinder body 4 is provided with the U-shaped tube bundles serving as heat transfer elements, and the lower half portion of the cylinder body 4 is provided with the cantilever combined coils 14 serving as heat transfer elements. In the assembly of the heat exchanger, firstly fastening the U-shaped tube bundles 11 onto the tube plate in an expanded joint way, parallelly connecting the cantilever combined coils 14 onto the heat medium tube by means of bolts, welding the container flange 2 to both ends of the cylinder body, the upper shell cover 1, and the lower shell cover 5 respectively; then welding the cantilever combined coils 14 together with the partition plate within the cylinder body 4; finally joining the cylinder body 4, the upper shell cover 1, the lower shell cover 5, and the tube plate which is in an expanded way jointed with the U-shaped tube bundles, integrally into one unitary by means of bolts, thus completing the assembly of the main body of the heat exchanger. Between the flanges and between the flanges and the tube plate of the heat exchanger are provided with sealing gaskets, which are subject to the pressure above 1.6 Mpa under the general operating condition. Dependent on different heat exchanging demands, a partition plate can be arranged in the upper shell cover 1 of the heat exchanger, so as to establish different tube pass.

The arranging manner of the cantilever combined coils 14 in the present heat exchanger differs from that of the conventional tubular type heat exchange elements, thereby completely eliminating the need of the tube-plate coupling structural fashion, and instead directly connecting the cantilever combined coils in a plurality of groups onto the hot media tube in parallel. The structural form of the cantilever combined coils 14 sets the heat exchange elements free out of the conventional tube-plate structure, so that the spatial arrangement of the heat exchanger is made more flexible, and the steam-water and water-water complex heat exchange within the same one shell can be realized.

Under the inducement of the pulsating flow, the energy distribution over the cantilever combined coils 14 at respective natural frequency has a significant influence on the operating condition of the cantilever combined coil bundles. Upon experiments, the bending radius, and the diameter and the wall thickness of the circular tube of the cantilever combined coils can be screened out to determine the specific dimensions of the different models, so that such constructed induction vibration system as above makes the variation of the water velocity not have a significant influence on the vibration, consequently, the cantilever combined coils can be adapted to the variation of different loads, while maintaining good vibration characteristics.

The heat exchange efficiency of the present heat exchanger is more than 98%, and the maximum heat exchange capacity is 7 MW, and on the other hand, the heat source is generally saturated steam at the pressure 0.6 MPa. The present heat exchanger can maintain the production output quite well, even when the steam pressure reduces to 0.1 MPa. The advantages of the present heat exchanger include the small size, the simple construction, a high energy utilization rate, etc., therefore, the present heat exchanger can be a new generation product relative to the currently-used conventional low-temperature, low-pressure and corrosion-free heat exchangers.

Which the invention has been described with reference to the preferred embodiments, obvious modifications and alternations are possible by those skilled in the related art. Therefore, it is intended that the invention include all such modifications and alternations to the full extent that they come within the scope of the following claims or the equivalents thereof. 

1. A complex flow path type heat exchanger having U-shaped tubes and cantilever combined coils, characterized in that, the same one fluid has the different flow routes in different flow paths, and in that after entering into the heat exchanger, steam is firstly cooled and condensed on the shell side of U-shaped tubes, then enter into a plurality of groups of cantilever combined coils within the same one shell for a secondary heat exchange, subsequently flows out of the heat exchanger after being subcooled; and in that at first water to be heated is preliminarily heated on the shell side of a portion of a cylinder body provided with cantilever combined boils, then enters into the tube of U-shaped heat exchange tube bundles, in order to be heated up to the desired temperature, thereafter flows out of the heat exchanger through a heated water outlet pipe.
 2. A complex flow path type heat exchanger having U-shapes tubes and cantilever combined coils according to claim 1, characterized in that, it comprises a plurality of groups of the cantilever combined coils parallely connected onto the hot medium tube, and in that the cantilever combined coils have a fixed end, an absolutely free end, and a relatively free end, so that vibration can be generated under fluid induction. 